• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.533-539
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• 2018

In this paper, the transformer type superconducting fault current limiter (SFCL) with additionally coupled circuit was suggested and its peak fault current limiting characteristics due to the fault condition to affect the fault current were analyzed through the fault current limiting tests. The suggested transformer type SFCL is basically identical to the previous transformer type SFCL except for the additional coupled circuit. The additional coupled circuit, which consists of the magnetically coupled winding to the primary and the secondary windings together with another superconducting element and is connected in parallel with the secondary winding of the transformer type SFCL, is contributed to the peak fault current limiting operation for the larger transient fault current directly after the fault occurrence. To confirm the fault current limiting operation of the suggested SFCL, the fault current limiting tests of the suggested SFCL were performed and its effective peak fault current limiting characteristics were analyzed through the analysis on the electrical equivalent circuit.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.29-34
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• 2001

A Bi-2223 tape has been developed for low-field Power applications such as Power cables or transformers working at liquid nitrogen temperature For such applications it is required to understand fault current characteristics of the Bi-2223 tape. In this paper we report fault current characteristics using two types of samples, straight sample and pancake coil sample. It was found that the fault current characteristics of the Bi-2223 tape are independent of external fields and frequencies . However they depend on electrical insulations and fault durations strong1y Also it was shown that the fault current characteristics in the insulated straight sample are similar to those in the pancake sample with a conductor insulation. Finally. it was shown that the Pancake sample with a layer insulation has better characteristics than that with a conductor insulation fur fault currents.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.134-139
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• 2013

When the accident occurred in power distribution system, it needs to control efficiently the fault current according to the fault angle and location. The flux-lock type superconducting fault current limiters (SFCL) can quickly limit when the short circuit accidents occurred and be made the resistance after the fault current. The flux-lock type SFCL has a single triggering element, detects and limits the fault current at the same time regardless of the size of the fault current. However, it has a disadvantage that broken the superconductor element. If the flux-lock type SFCL has separated structure of the triggering element and the limiting element, when large fault current occurs, it can reduce the burden of power and control fault current to adjust impedance. In this paper, this system is composed by triggering element and limiting element to analyze operation of limiting current. When the fault current occurs, we analyzed the limiting and operating current characteristics of the two triggering current level, and the compensation characteristics of bus-voltage sag according to the fault angle and location.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.117-122
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• 2015

Our research team proposed a flux-offset type fault current limiter as a new limiter. The flux-offset type fault current limiter uses a fault current limit technology based on the flux offset principle of the primary and secondary windings of a transformer. Stable fault current limit characteristics were achieved through a preliminary study. However, it was discovered that the initial fault current was not limited. Therefore, in this paper, a high-speed interrupter and a superconducting element were separately applied to the secondary winding of the flux-offset type fault current limiter and the operating characteristics were comparatively analyzed. In the experiment, when the superconducting element was applied to the secondary winding of the transformer, the initial fault current was limited while the limitation in the operation time was further shortened.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.141-146
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• 2011

When the current of the superconducting element exceeds its critical current by the fault occurrence, the quench of the high-$T_C$ superconducting fault current limiter (HTSC) comprising the flux-lock type superconducting fault current limiter (SFCL) occurs. Simultaneously, the magnetic flux in the iron core induces the voltage in each coil, which contributes to limit the fault current. In this paper, the fault current limiting characteristics of the flux-lock type SFCL as well as the load voltage sag suppressing characteristics according to the flux-lock type SFCL's winding direction were investigated. To confirm the fault current limiting and the voltage sag suppressing characteristics of the this SFCL, the short-circuit tests for the simulated power system with the flux-lock type SFCL were carried out. The flux-lock type SFCL designed with the additive polarity winding was shown to perform more effective fault current limiting and load voltage sag suppressing operations through the fast quench occurrence right after the fault occurs and the fast recovery operation after the fault removes than the flux-lock type SFCL designed with the subtractive polarity winding.

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.40-44
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• 2017

This paper analyzed the fault current limiting characteristics of the previously proposed transformer superconducting fault current limiter (TSFCL) interruption system according to its transformer type. The TSFCL interruption system is an interruption technology that combines a TSFCL, which uses a transformer and a superconductor, and a mechanical DC circuit breaker. This technology first limits the fault current using the inductance of the transformer winding and the quench characteristics of the superconductor. The limited fault current is then interrupted by a mechanical DC circuit breaker. The magnitude of the limited fault current can be controlled by the quench resistance of the superconductor in the TSFCL and the turns ratio of the transformer. When the fault current is controlled using a superconductor, additional costs are incurred due to the cooling vessel and the length of the superconductor. When the fault current is controlled using step-up and step-down transformers, however, it is possible to control the fault current more economically than using the superconductor. The TSFCL interruption system was designed using PSCAD/EMTDC-based analysis software, and the fault current limiting characteristics according to the type of the transformer were analyzed. The turns ratios of the step-up and step-down transformers were set to 1:2 and 2:1. The results were compared with those of a transformer with a 1:1 turns ratio.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.289-293
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• 2007

The fault current limiting characteristics of the separated and the integrated three-phase flux-lock type superconducting fault current limiters (SFCLs) were analyzed. The three-phase flux-lock type SFCL consisted of three flux-lock reactors and three $high-T_c$ superconducting (HTSC) elements. In the integrated three-phase flux-lock type SFCL, three flux-lock reactors are connected on the same iron core. On the other hand, three flux-lock reactors of the separated three-phase flux-lock type SFCL are connected on three separated iron cores. The integrated three-phase flux-lock type SFCL showed the different fault current limiting characteristics from the separated three-phase flux-lock type SFCL that the fault phase could affect the sound phase, which resulted in quench of the HTSC element in the sound phase. Through the computer simulation applying numerical analysis for its three-phase equivalent circuit, the fault current limiting characteristics of the separated and the integrated three-phase flux-lock type SFCLs according to the ground fault types were compared.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.66-70
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• 2007

For the design to prevent the saturation of the iron core and the effective fault current limitation, the analysis for the operation of the flux-lock type superconducting fault current limiter (SFCL) with consideration for the hysteresis characteristics of the iron core is required. In this paper, the hysteresis characteristics of the flux-lock reactor, which is an essential component of the flux-lock type SFCL, were investigated. Under normal condition, the hysteresis loss of the iron core in the flux-lock type SFCL does not happen due to its winding structure. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. From the analysis for both the hysteresis curves and the fault current limiting characteristics due to the number of turns for the 1st and 2nd windings, the increase of the number of turns in the 2nd winding of the flux-lock type SFCL had a role to prevent the iron core from saturation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.499-504
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• 2016

In this paper, we analyzed the operational characteristics of the fault current limiting according to the amplitude of the fault current for the transformer type superconducting fault current limiter (SFCL). If the fault current happens, the superconducting element connected to the secondary coil is occurred quench and the fault current is limited. When the larger fault current occurs, the superconducting element connected to the third coil is occurred additional quench and the peak fault current is limited. We found that the fault current can be more effectively controlled through the analysis of the fault current limiting and the short-circuit tests.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.747-753
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• 2005

We Investigated the current limiting characteristics of the flux-lock type superconducting fault current limiter(SFCL) by fault angles. The flux-lock type SFCL consists of the primary and the secondary copper coils wound in parallel through the iron core and YBCO thin film. In this paper, the current limiting characteristics of the flux-lock type SFCL by fault angles in case of the subtractive and the additive polarity windings were compared and analyzed. The flux-lock type SFCL limited fault current more quickly as the fault angles increased. On the other hand, the initial power burden of the superconducting element during the fault increased as the fault angles increased. In addition, we found that the resistance of the flux-lock type SFCL in case of the subtractive polarity winding was more increased than that of the additive polarity winding. The peak current of the fault current in case of the subtractive polarity winding was larger than that of the additive polarity winding.